Conveyor track for heavy loads



Oct. l, i963 N. v. svENssoN CGNVEYOR TRACK FOR HEAVY LOADS Filed Dec. l5, 1960 United States Patent O 3,105,583 CNVEYOR TRACK FREEAVY LADS Nils V. Svensson, Goteborg, Sweden, assigner to Aktiebolaget Gotaveriren, Goteborg, Sweden, a corporation of Sweden Filed Dec. 15, 196i), Ser. No. '76,061 Claims priority, application Sweden Jan. 9, 1960 3 Claims. {(l. 193-38) In order to render possible long or short movements during the assembly of very large structure, it has been suggested, inter alia, to place the sections of the structure on carriages coupled with each other and movable on rollers along a horizontal or slightly sloping track. The object of the invention is to replace such carriages by a simple and inexpensive arrangement which in its broadest aspects is characterized in that elements consisting of a material having a low coefficient of friction and a high ability to support high loads without signiiicant compression are inserted as sliding members in a block displaceable on a sliptrack.

Two embodiments of the invention are. described with reference to the annexed drawings in which FG. l is a partially sectional view of abuilding-bed for ships with a hull mounted on sliding members according to the invention, FlG. 2 a similar sectional view of a modided sliding block, and FIG. 3 a top view of the block shown in PEG. 2.

Extending upwardly from the bottom of the bed l are two or more parallel ways 2 of concrete or similar material. The upper sides of the ways are covered with a strong U-beam 3 the flanges of which extend downwards along the sides of the ways. Mounted on the beams 3 is a sliptrack 4 which should be very smooth and advantageously consists of a plate of polished rustless steel or similar material which has the advantage of not being changed when exposed to wind and weather and also acts as an effective heat dissipating material. The sliptrack is horizontal or slightly sloping in the conveying direction. In any case, the inclination should not be so great as to cause the built-up structure to continue its movement by itself after having been started.

The ways form supports for sliding blocks which by means of a hydraulically or otherwise movable device are displaceable longitudinally or the ways and which support the structure which in the embodiment illustrated is represented by the hull 5 of a ship. Each sliding block cornprlses a strong steel beam 6 which preferably is l-shaped in cross-section and has vertical flanges. A block S consisting of a hard sort of wood, such as oak wood or beech wood, is inserted in such a manner between the downwardly extending flanges 7 that the ends of the anges 7 project below the lower side of the block 8 and surround the sides of the ways 2. Provided on the inner sides of the flanges 7 are bars 9 which are suitably spaced apart from the way 2 and are adapted to guide the sliding block laterally. In the lower side of the wooden block 8 there are provided recesses for a plurality of members lll which preferably consist of cylindrical vertically extending rests of such a height as to project outside the lower side of the block S. The material of the elements 1li should have a low coefficient of friction and a high ability to support high loads without significant compression. Examples of such materials are fluorine plastics, such as polytetrafluoroethylene and polymonochlorotrifiuoroethylene. Especially at high specific loads and low speeds, these materials have a very low coetiicient of frictions which furthermore is independent of temperatures up to 570 F. Wear can be reduced to negligible values if the material is mixed with iillers, such as graphite, in which case also the deformation under the iniluence of a long-lasting load becomes extremely small.

ddd-5,583

ICC

The elements lil are the only parts of the sliding bloclrs I 6 which are in Contact with the sliptrac.; 4, and, consequently, they must be able to withstand the whole load. Therefore, the dimensions of the projecting parts of the elements must be related to the total area of contact with the sliptrack such that the compression of the elements will not be so great as to allow the lower side of the block 8 to come into contact with the sliptrack. Further, the material of the block S should be able to distribute the forces applied to the elements 1i? and to transmit these forces to the steel beam 6.

if suitable, the structure 5 may be placed directly on the beam 6. However, to avoid damages, it is preferable to use a more soft support which can be easily obtained by the provision of longitudinally extending wooden beams ll which are placed between the upwardly extending flanges of the beam 6 so as to transmit the load to the sliding block.

A sliding block provided with sliding members as described above is able to slide easily on its track without the need of lubrication, which is highly important in View of the fact that the displacement of the structure resting thereon has to take place at shorter or longer intervals. ln a sliptrack which has to be lubricated to reduce friction, the lubricant will be squeezed out by the pressure during the periods of rest. Consequently, the start of the movement requires a greater force than the displacement itself, with the result that the drive mec .anism must be overdimensioned and t. at the movement becomes jerky and uncalculable so that it is not possible to determine with satisfactory accuracy where the movement will stop. These inconveniences are entirely eliminated by a sliding block devised in accordance with this invention.

The device illustrated in FlGS. 2 and 3 differs from the device shown in PIG. l mainly by the fact that the elements resting on the sliptrack are formed such as to permit measures to be taken to reduce the load on the elements. Similar parts appearing in both embodiments are designated with the same reference numerals. The elements l2 inserted in the wooden block 8 consist of rings of the above mentioned material. Three to five rings are provided in each sliding block and are spaced apart in the longitudinal direction of the block. Inside the inner periphery of the rings there are formed hollow spaces i3 between the sliptrack 14 and the wooden block S, which spaces can be connected by means of a conduit 15 with a source, not shown, of a fluid under pressure, such as oil under pressure or compressed air. lf iiuid under pressure is forced into the hollow space 13, the load on the elements l2 will be reduced and the sliding blocks can move more easily along the sliptrack ld. During the periods between the displacement of the sliding blocks the fluid need not be under pressure and the rings l2 may carry the whole load.

FIGS. 2 and 3 also illustrate a modilied supporting device for the structure 5. Instead of having the structure rest on the wooden beams ll associated with the sliding block, there are provided pairs of wooden wedges 16 placed in groups -transversely above the beams l1 and preferably above each of the rings 12 such that ian empty space is provided between the groups. Placed upon these wedges 16 is a wooden beam i7 on which the structure 5 rests. As a result thereof, parts of the Ilower side of the structure are exposed and can be painted or otherwise treated, whereupon other wedges and beams are placed under the finished surfaces and the previous wedges 16 and beams 17 are removed so that the work can be linished while the structure is resting on its supports.

The conveyor track need not be devised exactly as described above, it being merely important that the properties of the sliding members fulfil the named requirements. The beam 6 may be a welded box-shaped structure having its ends devised such `that the blocks can be placed close Ito each other and moved simultaneously by a force applied to one end block. The use of the conveyor track is not limited to the purpose indicated. It may be used wherever llarge and heavy structures are to be built and moved, such as for launching ships from conventional slips, provided that measures are taken to keep the temperature of the friction-surfaces :at a low level.

What I claim is:

1. in a conveyor track for heavy loads, a slip track Vbase having a smooth surface,

a block shaped sliding member of a hard material for carrying the load,

a number of recesses in the lower side of said .sliding members which faces `the track base,

and elements of uniform height made `from a material having a low coecient of friction and a high ability to support loads without significant compression tted into and retained by said recesses in such a manner that they are supported by the bottom thereof and project beyond said side of the sliding member.

2. In a conveyor track for heavy loads, a slip track base having a polished surface covering, a block shaped sliding member of a hard wood -for carrying the load,

a number of recesses in the lower side of said sliding member which faces the track base,

and cylindrical elements of uniform Iheight made from a fluorine plastic compound with a sui-table ller tzted into and retained by said recesses in such a manner that they are supported by the bottom thereof and project beyond said side of the sliding member.

3. In a conveyor track for heavy loads, a slip track base having a smooth surface,

a block shaped sliding member of a hard material for carrying the load,

a number of recesses in the lower side of said sliding member which faces t-he track base,

annular elements of uniform height made `from an antifriction material tted into and retained by said recesses in such a manner that they are supported by the bottom thereof and form a hollow space,

said elements projecting beyond said side of the sliding member, t

a source of pressure, and

means connecting said source with the hollow space of the annular element to permit said uid to carry part of the load.

Salvesen Aug. 9, 1904 Mancusi Oct. 21, 1958 

1. IN A CONVEYOR TRACK FOR HEAVY LOADS, A SLIP TRACK BASE HAVING A SMOOTH SURFACE, A BLOCK SHAPED SLIDING MEMBER OF A HARD MATERIAL FOR CARRYING THE LOAD, A NUMBER OF RECESSES IN THE LOWER SIDE OF SAID SLIDING MEMBERS WHICH FACES THE TRACK BASE, AND ELEMENTS OF UNIFORM HEIGHT MADE FROM A MATERIAL HAVING A LOW COEFFICIENT OF FRICTION AND A HIGH ABILITY TO SUPPORT LOADS WITHOUT SIGNIFICANT COMPRESSION 